Primary carpet backing

ABSTRACT

A primary carpet backing including a structure of at least three layers, wherein a first layer and a third layer including a nonwoven layer of fibers, and wherein a second layer which includes a reinforcement layer of fibers and is located between the first and the third layer, wherein the nonwoven layer of fibers of the first layer has an air permeability of at most 8000 L/m 2 ·s and the nonwoven layer of fibers of the third layer has an air permeability of at least 1000 L/m 2 ·s measured according to ISO 9237:1995, wherein the nonwoven layer of fibers of the first layer has a lower air permeability as the nonwoven layer of fibers of the third layer.

The application pertains to a primary carpet backing, a tufted carpet comprising the primary carpet backing and a method for producing such a tufted carpet comprising the primary carpet backing.

In traditional carpet tile productions there are many layers of different material behind the visible pile yarns. The construction behind the pile yarns comprises a primary carpet backing in which the pile yarns are tufted, and the primary carpet backing comprises a precoat to fixate the pile yarns. Below the tufted and precoated primary backing, a traditional carpet tile comprises a layer of polymer, a reinforcement layer, a further layer of polymer and optionally a secondary carpet backing.

This reinforcement layer can be e.g. a fiber glass nonwoven or a scrim, and is responsible for reinforcement in a direction in the plane (x- and y-dimension) of the carpet tile. To transfer occurring forces applied in x- and/or y-direction of the carpet tile to the reinforcement layer, layers of polymer coating are required between the primary carpet backing and the reinforcement layer, and between the secondary carpet backing and the reinforcement layer.

These layers of polymer coating are expensive and carpet tile producers seek to minimize the mass of these two layers of polymer coating, but, a minimum quantity of polymer is required as it is substantial for an adequate bonding between the reinforcement layer and the primary carpet backing and/or between the reinforcement layer and the secondary carpet backing.

In some carpet tiles the reinforcement layer was moved from between the two layers of polymer directly onto the secondary carpet backing, so that it is possible to reduce the two layers of expensive polymer coating to only one layer, and to reduce the total mass of polymer in the carpet tile.

WO 2011/069996 A1 discloses a primary carpet backing comprising a first and a second layer of fibers, wherein both are nonwoven layers of randomly laid fibers and the fibers of the first layer and the second layer comprise at least two different polymers.

WO 2016/00869 A1 discloses a polyvinyl chloride-free decorative surface comprising a reinforced layer, which is impregnated by a polyvinyl chloride-free paste. Thereby, the polyvinyl chloride-free paste is visible on both sides of the surface covering.

GB 1,409,068 discloses a method for providing a secondary backing to a tufted primary backing. Thereby, the reinforcement of the secondary backing is provided by longitudinal yarns being integral in the knitted structure, which are introduced during and as part of the knitting process.

However, although it is possible to reduce the number of layers of polymer coating by moving the reinforcement layer onto the secondary carpet backing, drawbacks occur like that additional adhesives have to be used to adhere the reinforcement layer onto the secondary carpet backing, and without being bound to theory it is believed that the moving of the reinforcement layer onto the secondary carpet backing has negative consequences for flatness stability (perpendicular to the plane of a carpet tile, z-dimension) like dishing or doming of the carpet tile.

Additionally, if a layer of polymer coating has a high affinity to the primary carpet backing, the polymer coating can be visible on the carpet face, which is known as latex bleeding.

The object of the present application is to provide a material for a primary carpet backing, a tufted carpet comprising the primary carpet backing and a method for producing such a tufted carpet comprising the primary carpet backing, which prevents or at least reduces the aforementioned drawbacks.

The object is reached by a material for a primary carpet backing comprising a structure of at least three layers, wherein a first layer and a third layer comprise a nonwoven layer of fibers, and wherein a second layer comprises a reinforcement layer of fibers and is located between the first and the third layer, characterized in that the nonwoven layer of fibers of the first layer has an air permeability of at most 8000 l/m²·s, and the nonwoven layer of fibers of the third layer has an air permeability of at least 3500 l/m²·s measured according to ISO 9237:1995, wherein the nonwoven layer of fibers of the first layer has a lower air permeability than the nonwoven layer of fibers of the third layer. Throughout this application, the terms “material for a primary carpet backing” and “primary carpet backing” will be used synonymously.

For clarity reasons, the measuring of the air permeability according to ISO 9237:1995 is performed at a pressure of 200 Pa and a sample having a sample size of 20 cm². Further, the feature that the nonwoven layer of fibers of the first layer has a lower air permeability than the nonwoven layer of fiber of the third layer is also called the “asymmetry of air permeability of the primary carpet backing” for reasons of readability and conciseness.

The fact that the primary carpet backing comprises a reinforcement layer of fibers improves the flatness stability perpendicular to the plane of a carpet tile (z-dimension), like dishing or doming of the carpet tile. The fact that the primary carpet backing comprises a third layer comprising a nonwoven layer of fibers having a minimum air permeability improves penetration of the precoat applied to the tufted primary carpet backing, while the first layer comprising a nonwoven layer of fibers having a reduced air permeability prevents latex bleeding of the precoat to the face of the carpet tile.

For clarity reasons, in the following are clarifications for some terms and phrases which are used during the application.

The term “composite” is to be understood as a material made from two or more constituent materials with significantly different physical or chemical properties that, when combined, produce a material with characteristics different from the individual components.

The phrase “substantially parallel” means that fibers of a unidirectional layer are spaced apart from each other so that the fibers do not contact adjacent fibers of the fibers of the unidirectional layer of fibers.

The terms “spunbonded” and “spun-laid”, mean the production of a nonwoven layer of fibers, wherein the fibers are extruded from a spinneret and subsequently laid down on a conveyor belt as a web of filaments and subsequently bonding the web to form a nonwoven layer of fibers, or by a two-step process wherein filaments are spun optionally drawn e. g. using drawing godets or a jet of pressurized air and wound on bobbins, e.g. in the form of multifilament yarns, followed by the steps of unwinding the multifilament yarns and laying the filaments down on a conveyor belt as a web of filaments and bonding the web to form a nonwoven layer of fibers.

The term “carpet face” has to be understood as the side of a carpet which is visible when a carpet is laid on a ground. In the case the carpet is laid on a ground, the side which is not visible is the side which exhibits backstitches of the tufting.

Within the scope of the present application it is understood that the term “fibers” refers to both staple fibers and filaments. Staple fibers are fibers which have a specified, relatively short length in the range of 2 to 200 mm. Filaments are fibers having a length of more than 200 mm. In an embodiment, filaments are fibers with a length of more than 500 mm. In an embodiment, filaments are fibers with a length of more than 1000 mm. Filaments may even be virtually endless, e.g. when formed by continuous extrusion and spinning of a filament through a spinning hole in a spinneret.

Within the scope of the present application “machine direction” is understood to be the direction of production, as it is the largest dimension of the primary carpet backing, which can also be synonymously called x-direction. Further, the “cross machine direction” is the second largest dimension of the primary carpet backing which is in plane with the machine direction and perpendicular to the machine direction, which can be synonymously called y-direction. Out of the plane and perpendicular to the machine direction and the cross machine is the third largest dimension of the primary carpet backing, which is the z-direction.

In an embodiment, the fibers of the nonwoven layer of fibers of the first layer and/or the fibers of the nonwoven layer of fibers of the third layer are filaments.

The primary carpet backing comprises a reinforcement layer of fibers, which can be composed of any suitable material, which is able to reinforce. There are several classes of material available: e.g. high modulus materials, low shrinkage materials and also materials which are resistant to compression.

All classes of materials have their own advantageous properties, for the stability of a primary carpet backing. High modulus materials add the advantageous property that the primary carpet backing has an increased stability against elongation. Low shrinkage materials add the advantageous property that the primary carpet backing has an increased stability against shrinkage, e.g. if temperatures above ambient temperatures impacts the primary carpet backing. Moreover, materials, which are resistant to compression, increase the stability of the primary carpet backing against compression, e.g. stiffness, if e.g. shrinking tufted yarns give a compression force onto the primary carpet backing.

In an embodiment, the fibers of the reinforcement layer of fibers have a tensile modulus of at least 25 GPa. In an embodiment, the fibers of the reinforcement layer of fibers have a tensile modulus of at least 40 GPa. In an embodiment, the fibers of the reinforcement layer of fibers have a tensile modulus of at least 50 GPa. In an embodiment, the fibers of the reinforcement layer of fibers have a tensile modulus of at least 75 GPa.

In an embodiment, the fibers of the reinforcement layer have a linear density of at most 50 tex. In an embodiment, the fibers of the reinforcement layer have a linear density of at most 40 tex. In an embodiment, the fibers of the reinforcement layer have a linear density of at most 30 tex. In an embodiment, the fibers of the reinforcement layer have a linear density of at most 28 tex. In an embodiment, the fibers of the reinforcement layer have a linear density of at most 20 tex. In an embodiment, the fibers of the reinforcement layer have a linear density of at most 15 tex.

In an embodiment of the present application the asymmetry of air permeability of the primary carpet backing is induced by the weight ratio of the nonwoven layer of fibers of the first layer and the nonwoven layer of fibers of the third layer, wherein it is desirable that the nonwoven layer of fibers of the first layer has a higher weight than the nonwoven layer of fibers of the third layer.

The weight ratio of the first layer and the third layer is at least 60:40. In an embodiment, the weight ratio of the first layer and the third layer is at least 70:30. weight ratio of the first layer and the third layer is at least 80:20. weight ratio of the first layer and the third layer is at least 90:10.

In an embodiment, the weight of the first layer comprising a nonwoven layer of fibers is at least 60 g/m². In an embodiment, the weight of the first layer comprising a nonwoven layer of fibers is at least 70 g/m². In an embodiment, the weight of the first layer comprising a nonwoven layer of fibers is at least 80 g/m². In an embodiment, the weight of the first layer comprising a nonwoven layer of fibers is at least 90 g/m². In all cases, the weight is determined accordance with ISO 9073-1.

In an embodiment, the weight of the third layer comprising a nonwoven layer of fibers is at most 40 g/m². In an embodiment, the weight of the third layer comprising a nonwoven layer of fibers is at most 30 g/m². In an embodiment, the weight of the third layer comprising a nonwoven layer of fibers is at most 20 g/m². In an embodiment, the weight of the third layer comprising a nonwoven layer of fibers is at most 10 g/m². The weight is determined in accordance with ISO 9073-1 in all cases.

Due to the higher weight of the nonwoven layer of fibers of the first layer, an increased surface coverage of the fibers in the nonwoven layer of fibers of the first layer and reduced surface coverage of the fibers in the nonwoven layer of fibers of the third layer can occur.

In an embodiment, the first layer comprising a nonwoven layer of fibers has a surface coverage between 1% and 40%. In an embodiment, the first layer comprising a nonwoven layer of fibers has a surface coverage between 2% and 30%. In an embodiment, the first layer comprising a nonwoven layer of fibers has a surface between 3% and 25%. In an embodiment, the first layer comprising a nonwoven layer of fibers has a surface between 5% and 20%. The surface coverage A is calculated in the following manner:

A=x*d;

with x being the number of filaments per filament layer and d being the diameter of the filaments. The number of filaments per layer x is calculated in the following manner:

${x = \frac{N}{L}};$

wherein N is the number of layers of filaments and L is the total length of filaments per area unit. The quantities N and L are calculated in the following manner:

${N = \frac{T}{d}};$

wherein d is the thickness of the filament in case monofilaments are used and wherein d is the thickness of the filament core in case bicomponent filaments are used.

L=M*t;

wherein T is the thickness of the first layer of fibers, M is the area weight of the first layer of fibers and t is the linear density of the filaments. The thickness T is determined in accordance with DIN ISO 9073-2 with a pressure foot of 25 cm² and a pressure of 0.05 kPa.

Without being bound to theory, an increased surface coverage of the fibers in the nonwoven layer of fibers of the first layer can lead to a lower air permeability, thus, inherently to a reduced permeability for fluids e.g., polymer coating and/or precoating.

Otherwise, a reduced surface coverage of the fibers in the nonwoven layer of fibers of the third layer can lead to a higher air permeability, thus, inherently to a higher permeability for fluids e.g. polymer coating and/or precoating.

In an embodiment, the third layer comprising a nonwoven layer of fibers has a surface coverage between 1% and 40%. In an embodiment, the third layer comprising a nonwoven layer of fibers has a surface coverage between 2% and 30%. In an embodiment, the third layer comprising a nonwoven layer of fibers has a surface between 3% and 25%. In an embodiment, the third layer comprising a nonwoven layer of fibers has a surface between 5% and 20%.

The asymmetry of air permeability of the primary carpet backing can also be introduced by different average diameters of the fibers comprised in the nonwoven layer of fibers of the first layer and in the nonwoven layer of fibers of the third layer.

In an embodiment, the fibers of the first layer have an average diameter which is smaller than an average diameter of the fibers of the third layer.

In an embodiment, the average diameter of the fibers of the nonwoven layer of fibers of the first layer is at most 50 μm. In an embodiment, the average diameter of the fibers of the nonwoven layer of fibers of the first layer is at most 30 μm. In an embodiment, the average diameter of the fibers of the nonwoven layer of fibers of the first layer is at most 25 μm. In an embodiment, the average diameter of the fibers of the nonwoven layer of fibers of the first layer is at most 20 μm.

In an embodiment, the average diameter of the fibers of the nonwoven layer of fibers of the third layer is at least 30 μm. In an embodiment, the average diameter of the fibers of the nonwoven layer of fibers of the third layer is at least 35 μm. In an embodiment, the average diameter of the fibers of the nonwoven layer of fibers of the third layer is at least 40 μm. In an embodiment, the average diameter of the fibers of the nonwoven layer of fibers of the third layer is at least 50 μm. In an embodiment, the average diameter of the fibers of the nonwoven layer of fibers of the third layer is at least 60 μm.

Without being bound to theory, it is believed that due to the smaller average diameter of the fibers of the nonwoven layer of fibers of the first layer and a higher average diameter of the fibers of the nonwoven layer of fibers of the third layer, differences in surface coverage by fibers in the nonwoven layer of fibers of the first layer and in the nonwoven layer of fibers of the third layer can be provided.

Reducing the average diameter of the fibers e.g. in the nonwoven layer of fibers of the first layer while keeping the weight of the layer constant, the value of length of fibers per square meter (m/m²) of nonwoven layer of fibers of the first layer, i.e. the fiber length per surface area, is increased which can lead to an increased surface coverage of the fibers in the nonwoven layer of fibers of the first layer.

Increasing the average diameter of the fibers e.g. in the nonwoven layer of fibers of the third layer while keeping the weight of the layer constant, the value of length of fibers per square meter (m/m²) of nonwoven layer of fibers of the third layer will be decreased, which can lead to a reduced surface coverage of the fibers in the nonwoven layer of fibers of the third layer.

Accordingly, without being bound to theory it is believed that by combining a higher weight of a layer of fibers and a smaller average diameter of the fibers of a layer, e.g. in the nonwoven layer of fibers of the first layer, can synergistically support the effect of a lower air permeability and a lower permeability for fluids e.g. polymer coating and/or precoating.

Otherwise, by combining a lower weight of a layer of fibers and a higher average diameter of the fibers of a layer, e.g. of the nonwoven layer of fibers of the third layer, can synergistically support the effect of a higher air permeability and a higher permeability for fluids e.g. polymer coating and/or precoating.

The nonwoven layer of fibers of the first layer and/or the nonwoven layer of fibers of the third layer can comprise mono-component fibers, two types of mono-component fibers and/or bicomponent fibers.

The nonwoven layer of fibers of the first layer and/or the nonwoven layer of fibers of the third layer can be made by any suitable process, such as a spun-laid process, air-laid process, wet-laid process, melt-blown process, or a carding process.

In an embodiment, the nonwoven layer of fibers of the first layer and/or the nonwoven layer of fibers of the third layer are made by a spun-laid process, wherein the fibers are made from a thermoplastic polymeric material. In the spun-laid process, bonding of the fibers of the nonwoven layer of fibers of the first layer and/or of the nonwoven layer of fibers of the third layer can be conducted by any suitable process, including hydro entanglement, needling, chemical bonding, calendaring, ultrasonic bonding, and other thermal bonding methods e.g. hot air bonding.

In an embodiment, the nonwoven layer of fibers of the first layer and/or the nonwoven layer of fibers of the third layer comprises two types of mono component fibers which comprise two chemically different thermoplastic polymeric materials, wherein two types of mono-component fibers differ in melting temperature by at least of 10° C. In an embodiment, the difference in melting temperature between the two thermoplastic polymeric materials is 20° C. In an embodiment, the difference in melting temperature between the two thermoplastic polymeric materials is 30° C. In an embodiment, the difference in melting temperature between the two thermoplastic polymeric materials is 50° C.

In an embodiment, the fibers of the nonwoven layers of fibers of the first layer and/or the fibers of the nonwoven layer fibers of the third layer are bicomponent fibers of the concentric or eccentric core/sheath model, side-by-side model, segmented pie model or island-in-the-sea model.

In an embodiment, the fibers of the nonwoven layer of fibers of the first layer and/or the fibers of the nonwoven layer fibers of the third layer are bicomponent fibers of the concentric core/sheath model, wherein the fibers are made of the same class of thermoplastic polymeric material or of chemically different thermoplastic polymeric materials.

Within the scope of the application, the same class of thermoplastic material means that same monomeric units of the polymer can be used, but the thermoplastic polymeric material can be different by a different polymer chain length, by a different density of the thermoplastic polymeric material or by a different orientation of the monomeric units, which can be isotactic, syndiotactic or atactic.

The core of the bicomponent fiber can comprise a thermoplastic polymeric material, which has a higher melting temperature as the thermoplastic polymeric material of the sheath. The melting temperature of the thermoplastic polymeric material of the core and the thermoplastic polymeric material of the sheath may differ by at least 10° C. The melting temperature of the thermoplastic polymeric material of the core and the thermoplastic polymeric material of the sheath may differ by at least 20° C. The melting temperature of the thermoplastic polymeric material of the core and the thermoplastic polymeric material of the sheath may differ by at least 30° C. The melting temperature of the thermoplastic polymeric material of the core and the thermoplastic polymeric material of the sheath may differ by at least 50° C.

The thermoplastic polymeric material of the fibers of the nonwoven layers of fibers of the first layer and/or the fibers of the nonwoven layer fibers of the third layer can be selected from a group comprising polyolefins such as polyethylene (PE) and polypropylene (PP), polyesters such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyetylene-1,2-furandicaboxylate (PEF), and poly lactic acid (PLA), polyamides such as polyamide 6,6 (PA6,6) and polyamide 6 (PA6), and copolymers and/or blends thereof.

In an embodiment, the fibers of the nonwoven layer of fibers of the first layer and/or the fibers of the nonwoven layer fibers of the third layer comprise at least 50 wt.-% of a thermoplastic material. In an embodiment, the fibers of the nonwoven layer of fibers of the first layer and/or the fibers of the nonwoven layer fibers of the third layer comprise at least 75 wt.-% of a thermoplastic material. In an embodiment, the fibers of the nonwoven layer of fibers of the first layer and/or the fibers of the nonwoven layer fibers of the third layer comprise at least 85 wt.-% of a thermoplastic material. In an embodiment, the fibers of the nonwoven layer of fibers of the first layer and/or the fibers of the nonwoven layer fibers of the third layer comprise at least 95 wt.-% of a thermoplastic material. In an embodiment, the fibers of the nonwoven layer of fibers of the first layer and/or the fibers of the nonwoven layer fibers of the third layer comprise at least 97 wt.-% of a thermoplastic material.

Thereby, the thermoplastic polymeric material can comprise additives such as flame retardants, coloring agents, fillers, fungicides, and/or anti-bacterial agents.

In an embodiment, the reinforcement layer comprised in the primary carpet backing can be a nonwoven fabric, a woven fabric, a laid scrim, a woven scrim, a unidirectional layer of fibers, or a knitted fabric.

In an embodiment, the reinforcement layer of the primary carpet backing is a laid scrim, a woven scrim or an unidirectional layer of fibers, wherein the fibers of the unidirectional layer of fibers are aligned substantially parallel to each other in the machine direction.

In an embodiment, the fibers of the unidirectional layer of fibers, which have huge length in view of width and height (e.g. filaments), are spaced apart from each other at a constant distance over the entire length of the unidirectional layer of fibers. Within the scope of this application, a constant distance may mean that the shortest distance between two threads does not differ by more than 2 millimeters. Within the scope of this application, a constant distance may mean that the shortest distance between two threads does not differ by more than 1 millimeters. Within the scope of this application, a constant distance may mean that the shortest distance between two threads does not differ by more than 0.5 millimeters.

As it is well known to the person skilled in the art, a scrim, no matter if laid or woven, is an open lattice structure composed of at least two sets of parallel threads, wherein the first group of parallel threads is oriented at an angle, generally at a 90° angle, to the second group of parallel threads. The first group of parallel threads may be connected to the second group of parallel threads by chemical bonding to form a laid scrim or the first group of parallel threads may be interwoven with the second group of parallel threads to form a woven scrim. In an embodiment, the openings in the scrim have at least one dimension in the plane of the scrim being at least 1 mm. In an embodiment, the openings in the scrim have at least one dimension in the plane of the scrim being at least 2 mm. In an embodiment, the openings in the scrim have at least one dimension in the plane of the scrim being at least 5 mm.

In an embodiment, the reinforcement layer of fibers comprised in the primary carpet backing comprises high modulus fibers is composed of a material selected from a group comprising glass, carbon, basalt, high modulus low shrinkage (HMLS) polyester, mineral material, aramid such as para aramid (PPTA) and meta aramid (MPTA), and ultra-high molecular weight polyethylene (UHMWPE).

In an embodiment, nonwoven layer of fibers of the first layer of the primary carpet backing can have an air permeability of at most 7000 l/m²·s. In an embodiment, nonwoven layer of fibers of the first layer of the primary carpet backing can have an air permeability of at most 6000 l/m²·s. In an embodiment, nonwoven layer of fibers of the first layer of the primary carpet backing can have an air permeability of at most 5000 l/m²·s. In an embodiment, nonwoven layer of fibers of the first layer of the primary carpet backing can have an air permeability of at most 4000 l/m²·s. In an embodiment, nonwoven layer of fibers of the first layer of the primary carpet backing can have an air permeability of at most 3000 l/m²·s. In an embodiment, nonwoven layer of fibers of the first layer of the primary carpet backing can have an air permeability of at most 2000 l/m²·s. In an embodiment, nonwoven layer of fibers of the first layer of the primary carpet backing can have an air permeability of at most 1000 l/m²·s. The air permeability is measured according to ISO 9237:1995 in all cases.

In an embodiment, the nonwoven layer of fibers of the second layer and/or third layer of the primary carpet backing can have an air permeability of at least 5000 l/m²·s. In an embodiment, the nonwoven layer of fibers of the second layer and/or third layer of the primary carpet backing can have an air permeability of at least 65000 l/m²·s. In an embodiment, the nonwoven layer of fibers of the second layer and/or third layer of the primary carpet backing can have an air permeability of at least 8000 l/m²·s. In an embodiment, the nonwoven layer of fibers of the second layer and/or third layer of the primary carpet backing can have an air permeability of at least 9500 l/m²·s. In an embodiment, the nonwoven layer of fibers of the second layer and/or third layer of the primary carpet backing can have an air permeability of at least 12000 l/m²·s. The air permeability is measured according to ISO 9237:1995 in all cases.

The object is also solved by a tufted carpet comprising a primary carpet backing according to any of the aforementioned embodiments, pile yarns tufted into the primary carpet backing, optionally a secondary carpet backing, adjoining on the side of the primary carpet backing which is not the carpet face, and/or optionally a precoat and/or a polymer coat.

Without being bound to theory, it is believed that due to asymmetry of air permeability of the primary carpet backing the precoat and/or the polymer coat is able to diffuse through the third layer and the second layer having a higher air permeability. Further, it is believed that due to the lower air permeability of the first layer of the primary carpet backing, the first layer acts as a barrier layer and does not permit or at least limits the precoat and/or polymer coat to diffuse through, which prevents or at least reduces latex bleeding.

In an embodiment, the secondary carpet backing can comprise a reinforcement layer of fibers which can be composed of any suitable material which is able to reinforce. There are a few classes of material available: e.g. high modulus materials, low shrinkage materials and also materials which are resistant to compression.

Without being bound to theory, it is believed that positioning of the secondary carpet backing directly next to the primary carpet backing will further reduce dishing and doming of the tufted carpet.

The reinforcement layer of the secondary carpet backing can be a nonwoven fabric, a woven fabric, a scrim, a unidirectional layer of fibers, or a knitted fabric.

In an embodiment, the reinforcement layer of the secondary carpet backing is a laid scrim, a woven scrim, or a unidirectional layer of fibers, wherein the fibers of the unidirectional layer of fibers are aligned substantially parallel to each other in the machine direction. Thereby, the fibers of the unidirectional layer of the secondary carpet backing are spaced apart from each other so that the fibers do not contact adjacent fibers of the unidirectional layer of fibers of the secondary carpet backing.

In an embodiment, the fibers of the unidirectional layer of fibers are spaced apart from each other at a constant distance over the entire length of the unidirectional layer of fibers.

In an embodiment, the reinforcement layer of the secondary carpet backing is made of high modulus fibers. The fibers may be composed of a material selected from a group comprising glass, carbon, basalt, high modulus low shrinkage (HMLS) polyester, mineral material, aramid such as para aramid (PPTA) and meta aramid (MPTA), ultra-high molecular weight polyethylene (UHMWPE).

In an embodiment the secondary carpet backing comprises a composite of at least three layers comprising two nonwoven layers of fibers and the reinforcement layer is located between the two nonwoven layers of fibers, wherein the secondary carpet backing has an air permeability of at least 1000 l/m²·s. In an embodiment the secondary carpet backing comprises a composite of at least three layers comprising two nonwoven layers of fibers and the reinforcement layer is located between the two nonwoven layers of fibers, wherein the secondary carpet backing has an air permeability of at least 3000 l/m²·s. In an embodiment the secondary carpet backing comprises a composite of at least three layers comprising two nonwoven layers of fibers and the reinforcement layer is located between the two nonwoven layers of fibers, wherein the secondary carpet backing has an air permeability of at least 5000 l/m²·s. In an embodiment the secondary carpet backing comprises a composite of at least three layers comprising two nonwoven layers of fibers and the reinforcement layer is located between the two nonwoven layers of fibers, wherein the secondary carpet backing has an air permeability of at least 7000 l/m²·s. In an embodiment the secondary carpet backing comprises a composite of at least three layers comprising two nonwoven layers of fibers and the reinforcement layer is located between the two nonwoven layers of fibers, wherein the secondary carpet backing has an air permeability of at least 9000 l/m²·s. In an embodiment the secondary carpet backing comprises a composite of at least three layers comprising two nonwoven layers of fibers and the reinforcement layer is located between the two nonwoven layers of fibers, wherein the secondary carpet backing has an air permeability of at least 10500 l/m²·s. In an embodiment the secondary carpet backing comprises a composite of at least three layers comprising two nonwoven layers of fibers and the reinforcement layer is located between the two nonwoven layers of fibers, wherein the secondary carpet backing has an air permeability of at least 12000 l/m²·s. The air permeability being measured according to ISO 9237:1995.

One or both of the nonwoven layers of fibers of the secondary carpet backing can have an average weight of at most 50 g/m². One or both of the nonwoven layers of fibers of the secondary carpet backing can have an average weight of at most 30 g/m². One or both of the nonwoven layers of fibers of the secondary carpet backing can have an average weight of at most 30 g/m². One or both of the nonwoven layers of fibers of the secondary carpet backing can have an average weight of at most 20 g/m². One or both of the nonwoven layers of fibers of the secondary carpet backing can have an average weight of at most 10 g/m². One or both of the nonwoven layers of fibers of the secondary carpet backing can have an average weight of at most 7 g/m².

In an embodiment, the average diameter of the fibers of one or both of the two nonwoven layers of fibers of the secondary carpet backing is at least 30 μm. In an embodiment, the average diameter of the fibers of one or both of the two nonwoven layers of fibers of the secondary carpet backing is at least 35 μm. In an embodiment, the average diameter of the fibers of one or both of the two nonwoven layers of fibers of the secondary carpet backing is at least 40 μm. In an embodiment, the average diameter of the fibers of one or both of the two nonwoven layers of fibers of the secondary carpet backing is at least 50 μm. In an embodiment, the average diameter of the fibers of one or both of the two nonwoven layers of fibers of the secondary carpet backing is at least 60 μm.

One or both of the two nonwoven layers of fibers of the secondary carpet backing can comprise mono-component fibers, two types of mono-component fibers and/or bicomponent fibers.

One or both nonwoven layer of fibers of the secondary carpet backing can be made by various processes: a spun-laid process, air-laid process, wet-laid process, melt-blown process, or a carding process.

In an embodiment, one or both nonwoven layers of fibers of the secondary carpet backing are made by a spun-laid process, wherein the fibers are made from a thermoplastic polymeric material. In the spun-laid process, bonding of the fibers of the nonwoven layer of fibers of the first layer and/or of the nonwoven layer of fibers of the third layer can be conducted by any suitable process, including calendaring, hydro entanglement, needling, ultrasonic bonding, chemical bonding, and other thermal bonding method e.g. hot air bonding.

In an embodiment, one or both nonwoven layers of fibers of the secondary carpet backing comprises two types of mono component fibers which comprises two chemically different thermoplastic polymeric materials, wherein the melting temperature of the different thermoplastic polymeric materials differs by at least by 10° C. In an embodiment, the melting temperature of the different thermoplastic polymeric materials differs by at least by 20° C. In an embodiment, the melting temperature of the different thermoplastic polymeric materials differs by at least by 30° C. In an embodiment, the melting temperature of the different thermoplastic polymeric materials differs by at least by 50° C.

In an embodiment, the fibers of one or both of the nonwoven layers of fibers of the secondary carpet backing are bicomponent fibers of the concentric or eccentric core/sheath model, side-by-side model, segmented pie model or island-in-the-sea model.

In an embodiment, the fibers of one or both of the nonwoven layers of fibers of the secondary carpet backing are bicomponent fibers of the concentric core/sheath model, wherein the fibers are made of the same class of thermoplastic polymeric material or chemically different thermoplastic polymeric materials.

The sheath of the bicomponent fibers of one or both nonwoven layers of fibers of the secondary carpet backing can comprise a thermoplastic polymeric material, which has a higher melting temperature as the thermoplastic polymeric material of the core. The melting temperature of the thermoplastic polymeric material of the sheath and the thermoplastic polymeric material of the core may differ by at least 10° C. The melting temperature of the thermoplastic polymeric material of the sheath and the thermoplastic polymeric material of the core may differ by at least 20° C. The melting temperature of the thermoplastic polymeric material of the sheath and the thermoplastic polymeric material of the core may differ by at least 30° C. The melting temperature of the thermoplastic polymeric material of the sheath and the thermoplastic polymeric material of the core may differ by at least 50° C.

The thermoplastic polymeric material of the fibers of both nonwoven layers of fibers of the secondary carpet backing can be selected from a group comprising polyolefins such as polyethylene (PE) and polypropylene (PP), polyesters such as polyethylene terephthalate (PET) polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN) polyetylene-1,2-furandicaboxylate (PEF), and poly lactic acid (PLA), polyamides such as polyamide 6,6 (PA6,6) and polyamide 6 (PA6), and copolymers and/or blends thereof.

In an embodiment, the fibers of both nonwoven layer of fibers comprise at least 50 wt.-% of a thermoplastic material. In an embodiment, the fibers of both nonwoven layer of fibers comprise at least 75 wt.-% of a thermoplastic material. In an embodiment, the fibers of both nonwoven layer of fibers comprise at least 85 wt.-% of a thermoplastic material. In an embodiment, the fibers of both nonwoven layer of fibers comprise at least 95 wt.-% of a thermoplastic material. In an embodiment, the fibers of both nonwoven layer of fibers comprise at least 97 wt.-% of a thermoplastic material.

Thereby, the thermoplastic polymeric material can comprise additives such as flame retardants, coloring agents, filler, fungicides, and/or anti-bacterial agents.

The tufted carpet according to the application can be manufactured by tufting a primary carpet backing, supplying a secondary carpet backing to the tufted primary carpet backing, on the side of the tufted primary carpet backing which is not the carpet face, and supplying a precoat into and/or onto the secondary backing from the side of the secondary carpet backing which is not facing the primary carpet backing, and optionally a polymer coating.

The primary carpet backing can be a composite being tufted, but it is also possible that the layers of the primary carpet backing are individual layers, which are adjoining each other, thus, the layers of the primary carpet backing are supplied individually to the tufting machine.

In an embodiment, the layers of the primary carpet backing are tufted as a composite. 

1. A material for a primary carpet backing comprising a structure of at least three layers, wherein a first layer and a third layer comprise a nonwoven layer of fibers, and wherein a second layer comprises a reinforcement layer of fibers and is located between the first and the third layer, wherein the nonwoven layer of fibers of the first layer has an air permeability of at most 8000 l/m²·s, and the nonwoven layer of fibers of the third layer has an air permeability of at least 3500 l/m²·s measured according to ISO 9237:1995, wherein the nonwoven layer of fibers of the first layer has a lower air permeability than the nonwoven layer of fibers of the third layer.
 2. The material according to claim 1, wherein a weight ratio of the first layer and the second layer is at least 60:40.
 3. The material according to claim 1, wherein the fibers of the first layer have an average diameter, which is smaller than an average diameter of the fibers of the third layer.
 4. The material according to claim 3, wherein the fibers of the first layer have an average diameter of at most 50 μm and/or the fibers of the third layer have an average diameter of at least 30 μm.
 5. The material according to claim 1, wherein nonwoven layer of fibers of the first layer and/or the nonwoven layer of fibers of the third layer comprise mono-component fibers, two types of mono-component fibers and/or bicomponent fibers.
 6. The material according to claim 1, wherein the nonwoven layer of fibers of the first layer and/or the nonwoven layer of fibers of the third layer are made by a spun-laid process, wherein the fibers are made from a thermoplastic polymeric material.
 7. The material according to claim 1, wherein the reinforcement layer is a laid scrim, a woven scrim or a unidirectional layer of fibers, wherein the fibers of the unidirectional layer of fibers are aligned substantially parallel to each other in the machine direction.
 8. The material according to claim 1, wherein the reinforcement layer is made of high modulus fibers or filaments.
 9. The material according to claim 1, wherein the nonwoven layer of fibers of the first layer has an air permeability of at most 7000 l/m²·s, measured according to ISO 9237:1995.
 10. The material according to claim 1, wherein the air permeability of the nonwoven layer of fibers of the third layer is of at least 5000 l/m²·s, measured according to ISO
 9237. 11. A tufted carpet comprising material according to claim 1, comprising pile yarns tufted into the primary carpet backing, optionally a secondary carpet backing, adjoining on the side of the primary carpet backing which is not the carpet face, and/or optionally a precoat and/or a polymer coat.
 12. The tufted carpet according to claim 11, wherein the secondary carpet backing comprises a reinforcement layer.
 13. The tufted carpet according to claim 12, wherein the secondary carpet backing comprises a composite of at least three layers comprising two nonwoven layers of fibers and the reinforcement layer is located between the two spunbonded nonwoven layers of fibers, wherein the secondary carpet backing has an air permeability of at least 1000 l/m²·s, measured according to ISO 9237:1995.
 14. The tufted carpet according to claim 13, wherein the fibers of the two nonwoven layer of fibers of the secondary carpet backing comprises have an average diameter of at least 30 μm.
 15. A process of producing a tufted carpet according claim 11 by tufting a primary carpet backing, supplying a secondary carpet backing to the tufted primary carpet backing, on the side of the tufted primary carpet backing which is not the carpet face, and supplying a precoat into and/or onto the secondary backing from the side of the secondary carpet backing which is not facing the primary carpet backing, and optionally a polymer coating. 